Monitoring of Vanuatu Scrubfowl burrows at Kurumambe, Tongoa, - - PowerPoint PPT Presentation

Monitoring of Vanuatu Scrubfowl burrows at Kurumambe, Tongoa, Vanuatu

VEAN

Location of Scrubfowl colonies monitored at Kurumambe, Tongoa

Location of monitored burrows on Kurumambe

West Coast, Cliff side North west coast.

Operating times of trial cameras at Kurumambe, Tongoa.

• 12 cameras were set – 1 of

which, A8, only operated successfully on the first day. This camera is not included in subsequent assessments.

• Other cameras worked for

between 50 and 495 days between 19th November 2016 and 28th March 2018.

50 100 150 200 250 300 350 400 450 500 A6 A11 B12 A10 B2 B5 A4 B13 A3 B9 B7 A8

No of Days active Burrow Location and Number

Nov-16 Dec-16 Jan-17 Feb-17 Mar-17 Apr-17 May-17 Jun-17 Jul-17 Aug-17 Sep-17 Oct-17 Nov-17 Dec-17 Jan-18 Feb-18 Mar-18

The number of Camera-days, by burrow, captured during the study period.

• No of camera-days per month

for the study period.

• Down arrows indicate dates

when cameras were reset.

• Camera A6 can be seen to have
• perated continuously

throughout the study period, while A11 was continuous for 12 months from November 2016.

50 100 150 200 250 300

Camera days Month

A6 A11 B12 A10 B2 B5 A4 B13 A3 B9 B7 A8

Diurnal variation in sightings of Vanuatu scrubfowl at nesting burrows in Kurumambe

• Scrubfowl are diurnal (a

surprising finding)– but with a peak in sightings in the first 3 hours after sunrise.

• Cameras were active continually

throughout night and day. No sightings of scrubfowl between 19.00hrs and 03.00hrs the next day.

Note that time of day is based on first time that bird was observed at site, even if length of

• bservation extended over more than 1 hour.

20 40 60 80 100 120 140 160 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

• No. of birds

Hour of Day

The number of Vanuatu scrubfowl recorded

• n camera by burrow.
• Data presented by colony and by
• burrow. Colony A is on the western

cliff, Colony B on the north west cliff.

• Markedly more birds at burrows 6 and

10 in Colony A. This is also where most laying attempts were reported – although burrow 13 at Colony B had similar rate of laying.

• Note that there is a 10-fold difference

between number of birds and number

• f laying instances.

Bird numbers (n=1115) are based on assumption that a new occurrence is reported when there is a minimum 10 minute gap between sightings on image. Laying events (n=71) are based on assumption that birds need to spend a minimum of 10 minutes in continuous view at the burrow. 0.000 0.100 0.200 0.0 0.5 1.0 1.5 2.0 B12 B2 A11 A3 A4 B9 B5 B13 A10 A6

Laying attempts per day Birds per day Burrow location and number

Variation in numbers and frequency of laying through the year.

• Peak laying period between June

and August – although high numbers also present in December.

• Laying periods recorded

throughout the year.

• Variation in bird numbers at sites

mirrors laying dates.

0.00 0.05 0.10 0.15 0.00 0.50 1.00 1.50 Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec

Laying events per day Birds per day

Bird/Day Lay/Day

Between year variation in time spent at 1 burrow.

• No. of birds recorded was

similar, but time spent, and number of times >10 minutes at the site was higher in 2016/17 than 2017/18.

• Local assessment was that there

were more birds in 2017/18 than 2016/17 – not supported by this evidence.

Data based on continuous camera activity at 1 site (A6) from 19th November to 27 March in both

• years. This was the only site where significant coverage in both years was achieved. It was the

site with most numbers, and highest occurrence rate of scrubfowl on the site.

141 138 2016/17 2017/18

No of observations Year

5:37:45 AM 3:38:38 AM 2016/17 2017/18

Length of Observations Year

10 6 2016/17 2017/18

Observations >10 mins Year

Timing and distribution of rat records, as recorded by trail cameras at Kurumambe

• There were 131 observations of

rats during the study period.

• Rats were recorded at 9 of the 11
• perating camera traps. The

number of rats varied between sites – with, maybe, more at the North west than the western site.

• Rats were exclusively recorded

during the nocturnal hours – between 18.00 and 05.30hrs.

• Most rats appeared to be R.

exulans – but ID from images is not reliable.

5 10 15 20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

No of Occurrences Hour of Day

1 2 2 2 12 20 33 5 10 15 20 25 30 35 B2 A11 B12 A10 A4 A3 B7 B13 A6 B5 B9

No Rats /100 days Burrow location and number

Timing and distribution of cat records, as recorded by trail cameras at Kurumambe.

• There were 208 observations of

cats during the study period.

• Cats were recorded at 9 of the

11 burrows monitored. There may have been more cats at the Western than the North Western colony.

• Cats were recorded at all times
• f the day – but with, maybe, a

peak in the hours before dawn.

5 10 15 20 25 1 2 3 4 5 6 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

No of cats Time of Day (hours)

0.0 0.0 0.6 1.6 1.9 3.8 7.5 9.1 13.3 13.9 25.9 5 10 15 20 25 30 A3 B7 B5 B2 B12 A11 B13 A10 A4 B9 A6

No Cats per 100days Burrow location and number

Conclusions - 1

• Scrubfowl were recorded at 10 of the 11 burrows that were

monitored – with behaviour indicating laying attempts being recorded at 4 of these burrows.

• Laying attempts were recorded on 1 in 10 days at the 3 most actively

used sites. Co-incidentally this is thought to be the laying rate of a single bird – 1 egg every 10 days.

• There are peaks in birds and laying behaviour in the months of June,

July and August – while there is a suggestion of a second peak at the turn of the year, December and January.

Conclusions - 2

• The two principal predators at the site are likely to be cats and, possibly, rats.
• Cats are known to be effective predators of scrubfowl chicks – and cameras here

recorded cats watching burrows at all times of day, possibly to capture chicks as they dig their way out of the burrow.

• Most rats seen appeared to be R. exulans – which is unlikely to be a significant
• predator. One or two images may better fit R. rattus – so this needs to be

investigated further.

• We saw few other, significant predators of scrubfowl at the site – although

Swamp Harrier is often seen quartering over the site.

Thank yu